kernel-install(8)

Pick the layout automatically. If the kernel is a UKI set layout to uki. If not default to bls if $BOOT/loader/entries.srel with content type1 or $BOOT/ENTRY-TOKEN exists, or other otherwise.

Leaving layout blank has the same effect. This is the default.

Added in version 254.

.RE

.PP $KERNEL_INSTALL_INITRD_GENERATOR and $KERNEL_INSTALL_UKI_GENERATOR are set for plugins to select the initrd and/or UKI generator. This may be configured as initrd_generator= and uki_generator= in install.conf, see below.

.PP $KERNEL_INSTALL_STAGING_AREA is set for plugins to a path to a directory. Plugins may drop files in that directory, and they will be installed as part of the loader entry, based on the file name and extension: Files named initrd* will be installed as INITRD-FILEs, and files named microcode* will be prepended before INITRD-FILEs.

.PP $KERNEL_INSTALL_ENTRY_NAME is set for the plugins to the resolved entry name, derived by expanding specifiers in the entry name format string. This is the base name (without file extension) used for UKI files, loader entry configuration files, and similar. By default this is ENTRY-TOKEN-KERNEL-VERSION, matching the traditional naming. See $KERNEL_INSTALL_ENTRY_NAME_FORMAT below for details on the available specifiers.

.SS "Environment variables understood by kernel-install"

.PP $KERNEL_INSTALL_CONF_ROOT can be set to override the location of the configuration files read by kernel-install. When set, install.conf, entry-token, and other files will be read from this directory only. Note that this path is relative to the host, and in particular symlinks in this directory are resolved relative to the host, even if --root=root is used. This means that it is generally not correct to use this variable to specify a directory underneath root if symlinks are used there.

.PP $KERNEL_INSTALL_PLUGINS can be set to override the list of plugins executed by kernel-install. The argument is a whitespace-separated list of paths. KERNEL_INSTALL_PLUGINS=: may be used to prevent any plugins from running.

.PP $MACHINE_ID can be set for kernel-install to override $KERNEL_INSTALL_MACHINE_ID, the machine ID.

.PP $BOOT_ROOT can be set for kernel-install to override $KERNEL_INSTALL_BOOT_ROOT, the installation location for boot entries.

.PP The last two variables may also be set in install.conf. Variables set in the environment take precedence over the values specified in the config file.

.PP $KERNEL_INSTALL_ENTRY_NAME_FORMAT can be set to configure the format string used to derive the entry name for boot loader entries and UKI files. The format string is expanded using specifier expansion. May also be configured as entry_name_format= in install.conf. The following specifiers are understood:

.sp
Table 1. Specifiers available in $KERNEL_INSTALL_ENTRY_NAME_FORMAT

.PP The resolved entry name must be a valid filename (no path separators). Defaults to %e-%v, which produces the traditional ENTRY-TOKEN-KERNEL-VERSION naming.

.PP For example, setting entry_name_format=%M_%A_%a on a system with IMAGE_ID=myos, IMAGE_VERSION=20250830, and architecture x86-64 would produce entry names like myos_20250830_x86-64.

.PP Note that the entry name is resolved at the time of each kernel-install invocation. If the format string uses specifiers that depend on mutable system state (e.g. %M, %A, %H), and that state changes between installing and removing a kernel, the remove operation may compute a different entry name than add did, leaving stale files on the boot partition. The entry_name_format= setting should therefore remain stable across a kernel's install/remove lifecycle. Additionally, the format should produce a unique name for each installed kernel, e.g. by including %v (kernel version) or %A (IMAGE_VERSION); otherwise installing multiple kernels will overwrite each other's boot entries.

.SH "EXIT STATUS"

.PP If every executable returns 0 or 77, 0 is returned, and a non-zero failure code otherwise.

.SH "FILES"

.PP /etc/kernel/install.d/*.install, /usr/lib/kernel/install.d/*.install